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Global and Local
Structural
Analysis and
Design
•
Structural
Modeling
•
Finite
Element Analysis
•
Structural
Evaluation
•
Optimization
•
Detailed
Stress Analysis
Ultimate
Longitudinal
Bending Strength
Overall
Structure
Vibration
•
Lightship
mass
distribution
•
Selfweight,
actual or scaled
•
Distributed
masses (e.g.,
weight curve)
•
Large
selected masses
(e.g., engines)
•
Hydrostatic
loads:
stillwater and
waves
•
Internal tank
fluid mass loads
•
Cargo masses
(containers &
bulk cargo)
•
Accelerations
(6 d.o.f.)
•
Pressure
loads, actual
and design
•
Point loads
(forces and/or
moments)
•
External
bending moment
and shear force
at ends of
partial models
Overall
Failure Modes
OVERALL
STRUCTURE
•
Progressive
collapse
•
Fatigue
•
Bending
deflection limit
•
Bending
stress limit
•
Static
•
Low frequency
•
Waves,
live loads
•
Medium
frequency
• Vibration
•
Slamming
CYLINDER
COLLAPSE
• General
buckling
• Bay
buckling
• Local
buckling
Individual
Member Failure
Modes
PANELS
• Collapse
•
Stiffener
flexure
•
Combined
buckling
•
Membrane
yield
•
Stiffener
buckling
• Stiffener
yield
•
Compression,
plate & flange
•
Tension,
plate & flange
• Plate
unserviceability
•
Yield :
Transverse
bending
Longitudinal
bending
•
Compression,
plate & flange
•
Local
buckling
•
Allowable
permanent set
Pressure loads
Concentrated
loads
GIRDER
• Collapse
•
Torsional
buckling
•
Plastic
buckling, flange
•
Plastic
buckling, plate
• Yield
•
Compression,
plate & flange
•
Tension,
plate & flange
FRAME
• Collapse,
plastic hinge
• Yield
•
Compression,
plate & flange
•
Tension,
plate & flange
Hogging-sagging
conditions of
the FFG frigate
hull (global
model)
Figure:
Structural
idealization as
an assembly of
plate-stiffener
separation
models (left) or
plate-stiffener
combination
models (middle)
or
stiffened panel
models (right)
Axial stress
distributions at
ULS for the
frigate test
hull under
sagging (left)
and hogging
(right)
Von Misses
stress
distributions at
ULS for the
frigate test
hull under
sagging (left)
and hogging
(right)
Axial stress
distributions at
ULS for the uni-directional
double-skin
tanker test hull
under sagging
(left) and
hogging (right)
Axial stress
distributions at
ULS for the uni-directional
double-skin
tanker test hull
under sagging
(left) and
hogging (right)
Von Mises stress
distributions at
ULS for the uni-directional
double-skin
tanker test hull
under sagging
(left) and
hogging (right)
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